Munising Formation

Munising Formation Stratigraphic range: Cambrian PreЄ Є O S D C P T J K Pg N

The Munising Group or Formation is a Cambrian sedimentary unit 1,700 feet (520 m) thick that crops out in Michigan and (to a lesser extent) Ontario. At one end of its extent, it comprises a basal comglomerate overlain by the Chapel Rock Member and the Miners Castle Member; elsewhere, it comprises the Eau Claire, Galesville (=Dresbach), and Franconia formations. Anhydritic evaporite deposits are present in places.^[1] The conglomerate was deposited by rivers in flood, with the Chapel Rock member, which contains deltaic deposits, representing transgression as the conglomerate cones sunk and became submerged; the Miners Castle member was deposited further from the shoreline, representing shelf deposits.^[2] Its uppermost strata may be Early Ordovician in age, and contain conodonts, trilobites and phosphatic moulds of brachiopods, ostrocoderm fish and gastropods.^[3]

References

1. ^ Paul A. Catacosinos (1973). "Cambrian Lithostratigraphy of Michigan Basin". The American Association of Petroleum Geologists Bulletin 57 (12): 2404–2418. 
2. ^ Charles a. Haddox, R. H. D. (1990). "Cambrian Shoreline Deposits in Northern Michigan". SEPM Journal of Sedimentary Research. doi:10.1306/212F9250-2B24-11D7-8648000102C1865D.  edit
3. ^ Miller, J. F.; Ethington, R. L.; Rose, R. (2006). "Stratigraphic Implications of Lower Ordovician Conodonts from the Munising and Au Train Formations at Pictured Rocks National Lakeshore, Upper Peninsula of Michigan". PALAIOS 21 (3): 227–237. doi:10.2110/palo.2004.p04-50.  edit